The invention relates to fabric articles that generate heat/warmth upon application of electricity.
Fabric or fibrous heating/warming articles are known, e.g., in the form of electric blankets, heating and warming pads and mats, heated garments, and the like. Typically, these heating/warming articles consist of a body defining one or a series of envelopes or tubular passageways into which electrical resistance heating wires or elements have been inserted. In some instances, the electric resistance heating wires are integrally incorporated into the body during its formation, e.g. by weaving or knitting. Relatively flexible electric resistance heating wires or elements, e.g., in the form of a core of insulating material, e.g., yarn, about which is disposed an electrical conductive element, e.g., a helically wrapped metal wire or an extruded sheath of one or more layers of conductive plastic, have been fabricated directly into the woven or knitted structure of a fabric body.
According to one aspect of the invention, a fibrous article adapted to generate heat upon application of electrical power comprises a fibrous body comprised of non-conductive fibers, a plurality of spaced apart electrical resistance heating elements in the form of conductive elements joined in the fibrous body with the non-conductive fibers and extending generally between opposite edge regions of the fibrous body, and electrical conductor elements extending generally along the opposite edge regions of the fibrous body and adapted to connect the plurality of spaced apart electrical resistance heating elements in a parallel electrical circuit to a source of electrical power, the fibrous body having a technical face and a technical back, with fleece on at least one of the technical face and the technical back formed by finishing non-conductive fibers of at least one of the technical face and technical back in a manner to avoid damage to electrical conductivity performance of the conductive elements joined with the non-conductive fibers in the fibrous body.
Preferred embodiments of this aspect of the invention may include one or more of the following additional features. The electrical conductor elements are adapted for connecting the plurality of spaced-apart electrical resistance heating elements in the parallel electrical circuit to a power source of alternating current, or to a power source of direct current, e.g., a battery, which may be mounted to the fibrous body. Series of at least three electrical resistance-heating elements are symmetrically spaced and/or series of at least three electrical resistance-heating elements are asymmetrically spaced. The fibrous body comprises a body that may be formed, e.g., by knitting, e.g., to form a reverse plaited circular knitted body or a double knit body consisting of two, separate fibrous sheets joined by interconnecting fibrous elements; by weaving; by tufting or needling; by felting; or by laying up fibers to form a non-woven fibrous web. The fibrous body may comprise hydrophilic material and/or hydrophobic material. In terry knit products, the technical face is formed of a stitch yarn and the technical back is formed of a loop yarn; preferably, the loop yam forms loops that overlay the stitch yarn at the technical face and forms loops at the technical back. The fibrous body may have loops formed only in a center region. The fibrous body has fleece formed in non-conductive fibers upon both the technical back and technical face. The conductive elements have the form of a conductive yarn, e.g., a stitch yarn. The electrical conductor elements, at least in part, are applied as a conductive paste or as a conductive hot melt adhesive. The electrical conductor elements comprise a conductive wire. The conductive elements comprise one or more of: a core of insulating material, an electrical resistance heating filament, e.g., disposed generally about the core, and a sheath material generally surrounding the electrical resistance heating filament (and the core). The core comprises synthetic material, e.g., polyester. The electrical resistance-heating filament comprises at least one metal filament, and preferably at least three metal filaments, wrapped helically about the core. The metal filaments of the electrical resistance-heating element are formed of stainless steel. The electrical resistance-heating element has electrical resistance in the range of about 0.1 ohm/cm to about 500 ohm/cm. The sheath material comprises yarn wrapped about the electrical resistance-heating filament (and the core). The sheath material comprises synthetic material, e.g., polyester.
According to another aspect of the invention, a fibrous article adapted to generate heat upon application of electrical power comprises a fibrous body comprised of non-conductive fibers, a plurality of spaced apart electrical resistance heating/warming elements in the form of conductive elements joined in the fibrous body together with the non-conductive fibers and extending generally between opposite edge regions of the fibrous body, and electrical conductor elements extending generally along the opposite edge regions of the fibrous body and adapted to connect the plurality of spaced apart electrical resistance heating/warming elements in a parallel electrical circuit to a source of electrical power, the fibrous body having a face and a back, with fleece on at least one of the face and the back formed by finishing non-conductive fibers of at least one of the face and back in manner to avoid damage to electrical conductivity performance of the conductive elements joined with the non-conductive fibers in the fibrous body, and the fibrous body comprising a first fibrous layer and a second fibrous layer, and the plurality of spaced apart electrical resistance heating/warming elements of the fibrous body being disposed generally between the first fibrous layer and the second fibrous layer.
Preferred embodiments of this aspect of the invention may include one or more of the following additional features. The fibrous body comprises a double knit fibrous body and the first fibrous layer and the second fibrous layer are joined, in face-to-face relationship, by interconnecting fibrous elements, the plurality of spaced apart electrical resistance heating/warming elements of the fibrous body being positioned and spaced apart by the interconnecting fibers and joined by the conductors in a parallel circuit. The first fibrous layer and the second fibrous layer may be formed separately and joined in face-to-face relationship, with the plurality of spaced apart electrical resistance heating/warming elements of the fibrous body disposed therebetween; or the plurality of spaced apart electrical resistance heating/warming elements may be mounted upon a substrate, the substrate with the plurality of spaced apart electrical resistance heating/warming elements mounted thereupon being disposed between the first fibrous layer and the second fibrous layer; or the plurality of spaced apart electrical resistance heating/warming elements may be mounted upon at least one opposed surface of the first fibrous layer and the second fibrous layer. The first fibrous layer and second fibrous layer may be joined by laminating or by stitching. The substrate may comprise an open grid or a moisture-resistant, vapor permeable barrier material.
According to still another aspect of the invention, a fibrous article adapted to generate heat upon application of electrical power is formed by a method comprising the steps of: joining a stitch yarn and a loop yarn to form a fibrous prebody, with the loop yarn overlaying the stitch yarn at a technical face and forming in loops at a technical back of the fibrous prebody; at spaced-apart intervals, incorporating into the fibrous prebody as the stitch yarn an electrical resistance heating/warming element in the form of a conductive yarn; forming the fibrous prebody into a fibrous body, with the electrical resistance heating/warming elements extending between opposite edge regions of the fibrous body; in a manner to avoid damage to electrical conductivity performance of the electrical resistance heating/warming elements, finishing non-conductive fibers of at least one of the technical face and the technical back of the fibrous body to form a fleece surface region; and providing conductive elements for connecting the electrical resistance heating/warming elements, in parallel, to a source of electrical power.
Preferred embodiments of this aspect of the invention may include one or more of the following additional features. The method further comprises the step of joining the stitch yarn and the loop yarn by a reverse plaiting circular knitting process. The method further comprises the steps of: in a manner to avoid damage to electrical conductivity performance of the electrical resistance heating/warming elements, finishing non-conductive fibers of the technical face of the fibrous body to form a first fleece surface region; and in a manner to avoid damage to electrical conductivity performance of the electrical resistance heating/warming elements, finishing non-conductive fibers of the technical back of the fibrous body to form a second fleece surface region.
According to another aspect of the invention, a method of forming a fibrous article adapted to generate heat upon application of electrical power comprises the steps of: joining a stitch yarn and a loop yarn to form a fibrous prebody, the stitch yarn forming a technical face of the fibrous prebody and the loop yarn forming a technical back of the fibrous prebody, the loop yarn forming in loops that overlay the stitch yarn at the technical face and at the technical back of the fibrous prebody; at spaced-apart intervals, incorporating into the fibrous prebody as the stitch yarn an electrical resistance heating element in the form of a conductive yarn; forming the fibrous prebody into a fibrous body, with the electrical resistance heating elements extending between opposite edge regions of the fibrous body; in a manner to avoid damage to electrical conductivity of the electrical resistance heating elements, finishing non-conductive fibers of at least one of the technical face and the technical back of the fibrous body to form a fleece surface region; and providing conductive elements for connecting the electrical resistance heating elements, in parallel, to a source of electrical power.
Preferred embodiments of this aspect of the invention may include one or more of the following additional features. The method further comprises the step of joining the stitch yam and the loop yarn by a reverse plaiting circular knitting process. The method further comprises the steps of: in a manner to avoid damage to electrical conductivity of the electrical resistance heating elements, finishing non-conductive fibers of the technical face of the fibrous body to form a first fleece surface region, and, in a manner to avoid damage to electrical conductivity of the electrical resistance heating elements, finishing non-conductive fibers of the technical back of the fibrous body to form a second fleece surface region. The conductive yarn of the fibrous prebody comprises one or more of: a core of insulating material, an electrical resistance heating filament, e.g., disposed generally about the core, and a sheath material generally surrounding the electrical resistance heating element (and the core). The method further comprises the step of forming the sheath material by wrapping the electrical resistance-heating element (and the core) with fibrous elements. The method further comprises the step of connecting the conductive element to a source of electric power and generating heat. The method further comprises the step of connecting the conductive element to a source of electric power comprising, e.g., alternating current or direct current, e.g., a battery, which may be mounted to the fibrous article, and generating heat. The method further comprises the steps of: limiting formation of loops to a central region of the fibrous prebody, the central region being spaced from edge regions in the fibrous body, and providing the conductive elements for connecting the electrical resistance heating elements to a source of electrical power in the edge regions of the fibrous body. The method further comprises the step of rendering elements of the fibrous body hydrophilic and/or rendering elements of the fibrous body hydrophobic.
An objective of the invention is to provide fibrous electric heating/warming articles, e.g. electric blankets, heating and warming pads, heated garments, etc., into which a plurality of spaced-apart electric resistance heating members, in the form of conductive elements, are joined with non-conductive fibers, e.g., by knitting, weaving, tufting or needling, felting, laying up of a non-woven web, or any other suitable process. The fibrous body of the heating/warming article is subsequently subjected to a finishing process, e.g., non-conductive fibers at one or both surfaces of the body may be napped, brushed, sanded, etc., in a manner to avoid damage to electrical conductance of the electric resistance heating elements, to form fleece. In a planar structure, such as an electric heating blanket, the electric resistance heating members are connected at their ends along opposite edge regions of the planar body, i.e. of the blanket, and may be powered by alternating current or direct current, including by one or more batteries mounted to the fibrous heating/warming article.